Actuality. The high medical and social significance of ischemic stroke determines the search for new diagnostic and prognostic biomarkers, which can be microRNAs - non-coding RNAS of small length, which suppress the expression of protein-coding genes. Until now, no studies of the levels and role of microRNAs in patients with ischemic stroke have been conducted in Russia. The aim was to determine the levels of microRNA-21, 125, 126, 145 in plasma and buccal scraping in patients with ischemic stroke. Materials and methods. The study included 36 patients with acute ischemic stroke. A biomaterial for the study of microRNA-21, 125, 126, 145 in EDTA-plasma and bukkalno scrapings were taken on the 1st and 4th day from the beginning of the development of the disease. Determination of the level of microRNA included the stages of isolation, reverse transcription and real-time PCR. Statistical processing of the study data was carried out using software SPSS 8.0, Microsoft Excel 2013. Results. Statistically significant dynamics by 4 days of observation in patients with AI was revealed by levels of microRNA-125 in plasma, microRNA-126 in scraping and microRNA-145 in scraping. There were also statistically significant differences in the level of microRNA-126 in 1 and 4 days, and microRNA-125 in 4 days of observation. The development of the lethal outcome revealed statistically significant differences in the level of miRNA-125 in buccal scraping on 1 day, miRNA-145 in buccal scraping on 1 day and microRNA-21 in plasma on 1 day of observation. Also, the differences in such complications as pneumonia, pulmonary embolism, pyelonephritis. There were no statistically significant differences in the levels of miRNAs by type of AI, as well as by the presence and type of hemorrhagic transformation. Conclusion. MicroRNA-21, 125, 145 for 1 day of observation from the development of AI may have significance in the prognosis of fatal outcome, microRNA-21, 125 for 1 day in the forecast for the development of pneumonia, microRNA-125 for 1 day - the forecast PE, microRNA-126 on the 4th day - in the prediction of pyelonephritis. The revealed absence of differences in levels of microRNA-21 and 125 in scraping and plasma is a possible basis for the application of a non-invasive method of taking biomaterial for the study of microRNA.